Brain implant device

ABSTRACT

A brain implant device includes a housing containing communication and control electronics coupled to a conduit configured for monitoring signals from a brain&#39;s motor cortex and providing stimulation signals to the brain&#39;s sensory cortex. The brain implant device is capable of wireless communication with an external communication and control signal source by means of an antenna provided in the housing. The conduit is flexible and may contain upwards of 128 electrical conductors providing electrical connections between the device electronics and related sites on the motor and/or sensory cortex by means of a plurality of electrically conductive protuberances extending from the conduit and adapted for contact with such sites.

This application is a divisional of allowed U.S. application Ser. No.11/983,674 filed on Nov. 9, 2007; which claims the benefit under 35 USC119(e) of U.S. provisional application 60/857,890, filed on Nov. 9,2006. U.S. patent application Ser. No. 11/983,674 filed on Nov. 9, 2007,is a continuation in part of U.S. patent application Ser. No.11/173,863, filed Jul. 1, 2005, which claims the benefit under 35 USC119(e) of U.S. provisional application 60/586,368, filed on Jul. 7,2004.

THE FIELD OF THE INVENTION

The present invention is generally directed to implantable medicaldevices and in particular to a brain implant device in electricalcommunication with the brain's motor cortex and sensory cortex and inwireless communication with an external communication device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of an embodiment of a brain implantdevice in accordance with the present invention;

FIG. 2 is a front perspective exploded view of the invention of FIG. 1with the conduit separated from assembly 12;

FIG. 3 is a front cross-sectional view taken along lines 3-3 of FIG. 2;

FIG. 4 is a front perspective exploded view of the invention of FIG. 1with the conduit separated from assembly 12 and showing selected wireinterconnects;

FIG. 5 is a representation of a human body showing the placement ofimplanted micro devices;

FIG. 6 is a representation of a human body showing the progression ofsignals along a selected nerve path;

FIG. 7 is a further representation of a human body showing theprogression of signals along a nerve path and their relationship to thebrain's motor and sensory cortex;

FIG. 8 is a cross-section of a human skull showing the location of abrain implant device;

FIG. 9 is a perspective view of a brain implant device and the positionof electrode arrays on the brain's motor and sensory cortex;

FIG. 10 is a front cross-sectional perspective view of an alternateembodiment of the present invention;

FIG. 11 is an expanded view of the conductor containing passageways ofthe invention of FIG. 10;

FIG. 12 is a front perspective view of the underside of the invention ofFIG. 10;

FIG. 13 is a partial cutaway view of a human skull including animplanted brain implant device;

FIG. 14 is a top view of a human skull showing an outline of a cutout toreceive a brain implant device and associated conduit;

FIG. 15 is a schematic representation of a “helix” antenna;

FIG. 16 is a schematic representation of a “starburst” antenna; and

FIG. 17 is a schematic representation of a “zig-zag” antenna.

DETAILED DESCRIPTION

Turning first to FIG. 1 there is shown a representative perspective viewof a brain implant device (BID) 10 implemented in accordance with anembodiment of the invention. Such device 10 comprises an electronicspackage assembly 12, an electrical conduit 14, and at least oneelectrode array 16. As viewed in FIG. 1, multiple electrode arrays arecontemplated as exemplified by the addition of array 18. Still further,arrays coupled to conduit 14 are contemplated by the invention dependingupon the nature and extent of the particular application.

As shown in FIG. 1 the assembly 12 is generally circular in shape,however, other shapes such as square or oval, as mere examples, are alsocontemplated by the invention. A circular shape for assembly 12 ispreferable since, as will be shown later, the assembly 12 is typicallyembedded in a human skull which is typically most easily modified toaccommodate a circular assembly by the use of a surgical drill. Thediameter of the assembly 12 is in the range of about 15-25 mm andpreferably about 20 mm. The axial thickness 20 is about 5 mm. The BID 10is adapted to provide both sensory and stimulation capability to themotor cortex and the sensory cortex of the brain. As is recognized inthe field, unique sites in the brain are dedicated for controlling andsensing reactions of corresponding body elements. For example, there areportions of the brain that are associated with toes, ankles, feet,wrists, fingers, eyelids, lips, and so on. To this end, the BID 10includes 32 channels to control 32 individual body elements.Conceptually, the number of channels is far greater than 32 and isultimately dictated by the electronic capacity of the assembly 12.Moreover, more than one BID may be utilized in one application therebyincreasing overall BID capability accordingly.

Each channel comprises electronics for sensing body indicators such asneuron firing and muscle depolarization. Moreover, each channelcomprises electronics to provide electrical sensing of the brain motorcortex and electrical stimulus to the brain's sensory cortex. The basicelectronics sensory and stimulation functions are implemented, whenconsidering radio frequency energy generation techniques, in accordancewith the teachings of U.S. Pat. Nos. 5,358,514; 5,324,316; 5,193,539;and 5,193,540 which are assigned to the assignee hereof and which areincorporated herein by reference in their entireties. In addition, whenconsidering battery powered energy generation techniques, the sensingand stimulation functions are implemented in accordance with U.S. Pat.No. 6,185,452 which is assigned to the assignee hereof and isincorporated herein by reference in its entirety.

Stimulus and sense signals directed to specific brain sites are providedby electrode array 16 [and other arrays when required]. Such signals aregenerated in assembly 12 and carried by conduit 14 to the specifiedbrain sites. The conduit 14 preferably is a flexible multi-conductorconduit having dedicated conductors for each electrode (protuberance 32)in electrode array 16 [and 18 and so on, as required]. When configuredin a bipolar mode, one conductor is used per electrode in an electrodepair with one electrode of the pair acting as the source and the otherelectrode of the pair acting as the return. In a unipolar mode, oneconductor is used per electrode but the return is accomplished throughbody tissue and contact with a metallic surface on an assembly 12[otherwise identified as an indifferent electrode].

As shown in FIG. 1 conductors 22 and 24 representing two of a pluralityof conductors for array 16 and 18 respectively, extend from assembly 12along conduit 14 to electrode array 16. Although several conductorsshown for purposes of clarity, it is to be understood that a conductorexists for each electrode on an electrode array. The conduit 14 ispreferably flexible, capable of following the contour of the brainbetween the location of assembly 12 and the selected site on the brain.The conduit 14 is capable of being shaped in a zigzag manner when suchis required to meander between the assembly 12 and a desired brain site.A candidate conduit 14 is silicone rubber or polyimide with platinumconductors embedded in the silicone rubber, spaced apart so as to beinsulated one from another. The conductors, although preferably formedof platinum, may be selected from materials such as, but not limited to,copper, gold, silver, and alloys thereof. The conductors are typically 1mil in diameter and spaced apart one from an adjacent one about 1 mil.

Transfer of electrical signals from assembly 12 to conduit 14 is by wayof electrical connection between mating contacts on the assembly 12 andconduit 14. As shown in FIG. 2 contacts 26, 26′, 26″ and so on, for eachcontact are disposed on an outer surface 28 of assembly 12.Corresponding and mating contacts on conduit 14 are positioned at theconduit proximal end 30 so as to be in registration with correspondingcontacts on assembly 12. Accordingly, signals appearing on contacts 26,26′, 26″ and so on for all contacts, are transferred to correspondingcontacts on conduit distal end 31. Conduit 14 may be adhered to assembly12 by methods known in the art, such as for example, by medicaladhesives or bonding suitable for medical applications involvingimplantable devices. An alternate technique for adhering the conduit 14to the assembly 12 is by means of hermetically sealed electricalfeedthroughs such as described in U.S. Pat. Nos. 5,750,926 and 5,640,764both assigned to the assignee hereof and incorporated herein in theirentireties by reference.

Still further techniques for interconnecting sensory and stimulationelectrodes to an electronics assembly by means of a thin flexiblecircuit ribbon are described in detail in U.S. Pat. No. 7,142,909incorporated herein by reference in its entirety.

The electrode array 16 [18 and others as needed] includes a plurality ofelectrically conductive protuberances 32 extending substantiallyperpendicularly from array base 34. The individual conductors 22 areelectrically connected to corresponding and respective ones of theprotuberances 32. The distal tip of protuberance 32 is sufficientlysmall and sharp to be capable of making electrical contact with a singlecellular component of tissue, and in particular with brain tissue. Theprotuberances 32 extend from array base 34 with a range of heights fromapproximately 0.5 micrometers to about 100 micrometers. Theprotuberances 32 are adjacently spaced on array base 34 fromapproximately 0.5 micrometers to about 1000 micrometers from each other.Each protuberance 32 has a biocompatible insulating coat exclusive ofthe protuberance tip. An electrode array as presented herein isdescribed in detail in U.S. Pat. No. 4,969,468 which is assigned to theassignee hereof and is incorporated herein by reference in its entirety.

Signals monitored and supplied to electrode array 16 are processed byassembly 12 which is a hermetically sealed container comprising aceramic cup 36 closed at the open end by metallic cover plate 38. FIG. 3is a cross-sectional view of the assembly 12 of FIG. 2 taken along line3-3. The ceramic cup 36 is comprised of an insulating ceramic, such asfor example, zirconia, and metallic plate 38 is secured to cup 36 bymeans of brazing in a manner to hermetically seal the contents of thecup 36 from an external environment.

Other ceramic materials may include stabilized zirconia, partiallystabilized zirconia, yttria-stabilized zirconia, magnesium, calciumstabilized zirconia alumina, silicon nitride, silicon carbide, titaniumcarbide, tungsten carbide, titanium nitride, silicon oxynitridegraphite, titanium diboride, boron nitride and molybdenum disilicide.Prior to brazing, a “getter” may be introduced into the cup, so as tomaintain the interior region of the cup free of any gases or liquidcontaminant that may be introduced during manufacture and assembly. Themetallic plate 38 may comprise Ti64 titanium and a titanium containingalloy.

The brazing process is any one of a number of processes known in the artsuch as that described in U.S. Pat. No. 6,221,513. Contained withinassembly 12 is battery 40, timing and frequency source crystal 42, andchip stack 44. Battery 40 may be a rechargeable battery having a powercapacity in the range of about 2 milliamp hours per cubic centimeter.Candidate batteries may be formed of LI-I or LI-I-SN. The battery issized to be capable of providing power to a plurality of microsensor andmircostimulator electronics [hereinafter “micro device electronics”] aswell as to system electronics including processor and telemetrycircuits. Advantageously the battery 40 serves as a common power supplyfor each of the micro device electronics. In this manner, a singlerecharging circuit may be used in place of individual rechargingcircuits for each micro device electronics. The recharging circuitcomprises coil 46 which is wrapped around ferrite ring 48 and isinterconnected to a corresponding control chip in chip stack 44. Controlof battery charging by means of the battery control chip is implementedin a manner similar to that as taught in U.S. Pat. No. 6,185,452. Thecoil 46 is capable of being magnetically coupled to an external devicethat transmits a magnetic, ultrasonic or RF command signal for at leastcharging battery 40. Accordingly, the same coil 46 may be used forcharging the rechargeable battery 40 and for providing control andcommand signals in a manner consistent with the teachings of U.S. Pat.No. 6,185,452.

Referring again to FIG. 3 there is shown a capacitor and crystalassembly 42 mounted in proximity to battery 40. In particular, thecrystal assembly houses a crystal oscillator, serving as a very accurateclock source, as to provide real time scheduling and to provide areceiver and transmitter with a constant and accurate frequency source.Additionally, each of the 32 channels or the number of channels selectedfor a particular application is coupled to this crystal oscillator as toprovide complete frequency synchronization throughout and between allselected channels. Accordingly, any potential frequency mismatch betweenchannels may be avoided by having a common frequency source or clock forall selected channels. Use of a crystal, in a task scheduling mode forexample, is described in U.S. Pat. No. 6,164,284.

The capacitors mounted on assembly 42 are arranged and controlled toprovide stimulation pulses at the appropriate site on the brain sensorycortex. Each selected channel includes a corresponding capacitor sizedand charged to a stored energy value to provide brain detectable signalsto corresponding locations on the sensor cortex. Each of the capacitorsin assembly 42 are electrically coupled to respective ones of thecontact 26, 26′, and 26″, etc. through gating circuitry contained inchip stack assembly 44. Accordingly, the particular capacitor that isconnected through or by means of the chip set is dependant upon which ofthe protuberances 32 is designated to receive a stimulation signalprovided by the corresponding charged capacitor.

Mounted in proximity to the capacitors and crystal assembly 42 is chipstack assembly 44. The preferable packaging technique for chip stackassembly 44 is vertical stacking for the integrated circuits/chips andfor interconnection of conductors to interconnect selected contacts ofdifferent ones of the chips in the chip stack. A technique for such chipstacking and interconnect is described in U.S. Pat. No. 7,071,546assigned to the assignee hereof and incorporated herein in its entiretyby reference. The chip stack 44 contains communications and controlelectronics including amplifier electronics to enable sensing signalsfrom and stimulation of, a selected number of brain sites, dependingupon the muscle group selected to be activated. The present embodimentis configured to contain 32 individual amplifiers, however, 64 and 128amplifiers and beyond are well within the contemplation of theinvention. The circuit design requirements and configuration toundertake the stimulation and sensing functions are described in U.S.Pat. Nos. 5,358,514; 5,324,316; 5,193,539; and 5,193,540 as referencedabove.

Sensing and stimulation signals processed by chip stack 44 are carriedfrom the selected brain sites to assembly 12 by means of conduit 14. Aspreviously described, although not restricted to a specific material,conduit 14 is preferably formed of a flexible thin film electricallyinsulating material such as for example, Kapton or silicone. Kapton is aregistered trademark of E.I. DuPont Nemours Company. Embedded within theKapton are thin flexible electrically conductive wires such as platinumor gold or copper or alloys thereof that extend the length of theconduit 14 from the connection point with the protuberances 32 onelectrode array 16 [and 18, etc. if present] to the correspondingcontact 26 [26′, 26″, etc.] on assembly 12. As previously described, theconduit 14 is sufficiently flexible to conform to the contour of thetissue below the surface of the skull and maybe even configured in aserpentine like fashion to allow for a slight contraction or extensionof the conduit without the fear of dislodgement of the protuberances 32from the contact points on the brain. Each of the conductive wiresembedded within the Kapton, terminates at different specific ones ofcontacts located at the proximal end 30. For example, and with referenceto FIG. 4, conductor wire 22 is electrically and conductively attachedto contact 50 on the proximal end of conduit 14. Similarly, conductorwires 22′, 22″, and 22″ are electrically conductively attached tocontacts 50′, 50″, and 50″ respectively. When the conduit 14 is mountedtogether in contact with the assembly 12, conduit 14 is orientedrelative to the assembly 12 such that the contacts 50, 50′, 50″ and 50″,etc., are in registration and alignment with corresponding contacts 26,26′, 26″, and 26″, etc., on assembly outer surface 28. Reliableconductivity between contacts 50, 50′, etc. and 26, 26′, etc.respectively, may be accomplished, for example, through the use of “softbumps” each bump being positioned between each respective contact 50 and26. The soft bumps are formed of soft malleable electrically conductivematerial so that when the conduit proximal end 30 and the assembly 12are urged together, the bumps are slightly deformed due to contactpressure and reliable electrical connections are established betweenconduit contacts and the assembly contacts. This and other techniquesknown in the art may be used to establish reliable electrical contactsbetween the conduit 14 and assembly 12.

The conduit 14 may carry upwards of 128 wires and beyond, depending uponindividual system design requirements. In such case, each amplifier inchip set 44 may be selectively attached to five different contacts, thatis, two contacts for a sensing function, two contacts for a stimulationfunction, and one contact to an indifferent electrode. Switching betweeneach of these functional capabilities may be through switchingtechniques used and known in the art. Communication with externalelectronics is by way of antenna 52. Antenna 52 extendscircumferentially about coil 46, typically, in a dipole antennaconfiguration. The antenna is electrically coupled to receiver andtransmitter electronics [not shown] in chip set 44, for communicatingcommand and control signals to assembly 12 and to transmit sensory andstatus signals from assembly 12 to an external control circuit [notshown]. Communication frequencies, although not being limited to, arepreferably between 100 to 900 MHz. Communication techniques and signalprocessing techniques are consistent with those described in the abovereferenced patents assigned to the assignee hereof.

Although only a dipole antenna configuration has been described it is tobe understood that other antenna configurations are contemplated by theinvention as well. For example, one of the conductors 22 may be used asa single wire antenna in place of the dipole antenna 52. In such case,the conductor 22 preferably, would not be coupled to a respectiveprotuberance 32. In an alternate embodiment, for example, the outersurface 28 may be formed of a metallic material and the contacts 26,26′, etc. may be surrounded by electrically insulating feedthroughsknown in the art. In such case, the contacts 26 and 50 and so on, areelectrically insulated from the surface 28 and metallic cover plate 38may be coupled to a RF generator contained on chip set 44, so as to forman antenna to transmit signals generated by such RF generator. Tocommunicate with external electronics, the RF generator as well as,surface 28 and metallic cover plate 38, may be coupled to chip set 44 ina manner previously described, with the surface 28 and cover plate 38providing radiating antenna surfaces.

In practice, the BID 10 is used in conjunction with a master controllerand at least one implanted microstimulator/microsensor. A mastercontroller is capable of receiving signals from the BID 10 interpretingwhether it is a motor cortex signal, and if so, transmitting astimulation command to a corresponding selected microstimulator tostimulate a target muscle or target nerve. In the event that thereceived signal is a sensory signal, the master controller is capable oftransmitting a “recognition” signal generated by the target muscle ortarget nerve to the BID 10 which then provides a signal to the sensorycortex to indicate to the brain that commanded activity has occurred.Functional capability and electronic implementation for the mastercontroller, or as alternately identified as the system control unit, maybe found in U.S. Pat. Nos. 6,208,894 and 6,315,721 assigned to theassignee hereof and incorporated herein in their entireties byreference.

Continuity of motor cortex commands from the brain to a selectedmuscle/nerve group in a living body may be interrupted if the nervepathway is severed. In such case, desired commanded muscular reaction isinhibited. FIG. 5 shows the placement of a plurality ofmicrostimulators/microsensors 54 throughout a human body each placed inproximity to a muscle/nerve to be stimulated and locations wherecorresponding responsive reactions are to be sensed. Although onlyseveral microstimulators/microsensors are numerically identified, it isto be understood that all devices shown are equivalent in function.Further, master controller 56 is shown as being implanted, however, itis to be understood that the master controller 56 may also be locatedoutside the body within sufficient proximity to the body such thatreliable wireless communication with the microstimulator/microsensor 54and BID 10 may be undertaken.

To explain the overall process of directed stimulation and the resultingsensory signal feedback, an example would prove helpful. With referenceto FIG. 6 and for purposes of illustration, assume that the lifting of ahand 58 by means of rotation of elbow 60 is commanded. It is understoodthat the brain 62 as shown in FIG. 6 contains a motor cortex 64 and asensory cortex 66.

Broadly described, defined brain sites are dedicated to specific bodylocations and elements. As shown in FIG. 6, identified portions of themotor cortex are dedicated to, for example, the elbow, wrist, hand,fingers, etc. with each site further divided [not shown] to right andleft elbows, right and left wrists, etc. and the specific fingers oneach hand, etc. The sensory cortex 66 has corresponding sites to eachmotor cortex site. When the brain commands selected activity, such asrotation of an elbow, corresponding neuron activity occurs in thecorresponding motor cortex site. Such neuron activity normallytranslates into stimulation of nerves dedicated to muscle groupscontrolling rotary motion of the elbow, and under normal conditions, theelbow 60 rotates so that hand 58 lifts from its prior position to thedesired position. The progression of neural signals 68, originating inthe brain 62 and moving down the relevant nerve path 70, to thecorresponding elbow muscle/nerve group 72, is shown in FIG. 6 as 68[T₁], 68 [T₂], 68 [T₃], etc., where T₁<T₂<T₃, etc. Muscle movement andthe resulting muscular depolarization causes response signal carried bythe elbow muscle group nerve to be transmitted back to the elbow site onthe sensory cortex to provide a feedback signal to the brain indicatingthat the commanded action has occurred.

FIG. 7 shows hand 58 raised in position due to the rotation of elbow 60.The progression of the depolarization signal 74 back to thecorresponding elbow site in the brain's sensory cortex 66 is shown by 74[T₆], 74 [T₇], 74 [T₈], etc. where T₆<T₇<T₈ etc. In the event that therelevant nerve path is severed, it is understood that the control signalwill not reach the selected muscle group, and the commanded action willnot occur. In such case, a microstimulator/microsensor 54′ [see FIGS. 5,6 and 7] is placed downstream from where nerve 70 is severed. Themicrostimulator/microsensor 54′ serves to apply, when commanded to doso, an electrical stimulation signal on nerve 70 similar to thatnormally occurring after the issuance of a command from the brain. Tothat end, a protuberance 32 on array 16 is positioned precisely (seeFIG. 9) on the motor cortex 64 to detect “elbow” signals and to carrysuch signals corresponding to brain neuron activity to BID 10. BID 10transmits, typically by way of a wireless communication channel, auniquely coded message corresponding to signals detected at the “elbow”site of the brain motor cortex 64, to master controller 56. The mastercontroller 56 identifies the coded message and dispatches a commandsignal to the specific microstimulator/microsensor, and in this example54′, positioned to stimulate the nerve (in this example) 70 that causesthe initiation of the rotation of elbow 60. Upon completion of rotationof elbow 60, a depolarization signal is emitted by the muscle group 72which then travels up nerve 70 to microstimulator/microsensor 54′.Because the nerve 70 is severed at this location, the signal does notproceed to the sensory cortex. The depolarization signal, however, isdetected by microstimulator/microsensor 54′ which then dispatches acorresponding signal reception acknowledgement to master controller 56.The master controller 56 then dispatches a coded message, as in thedownlink mode by way of wireless communication, to BID 10. The BID 10then provides a signal via conduit 14 to the protuberances 32 that ispositioned to contact the brain site devoted to the elbow on the brain'ssensory cortex 66. In this manner, and effective feedback signal isapplied to the brain, indicating that the commanded body activity hasindeed been accomplished.

In an alternate embodiment of the present invention, the BID 10 isconfigured to transmit command signals and receive response signalsdirectly from a microstimulator/microsensor. In that regard, signals ata particular brain motor cortex site indicating desired activity for thecorresponding body element, are carried to the BID 10 by way of conduit14. Signals processed by the BID 10 are dispatched, typically bywireless communication to the specific microstimulator/microsensor 54dedicated to stimulate and monitor the body element corresponding to theparticular sensory cortex activity. Upon receipt of the command signal,microstimulator/microsensor 54′ [for the present example] provides astimulation signal to the nerve/muscle group dedicated to undertake thecommanded activity. Once the activity has been completed, thedepolarization signal is sensed by microstimulator/microsensor 54′, andan acknowledgement is dispatched again by wireless communication back tothe BID 10 which then provides an acknowledgement signal to the brain'ssensory cortex dedicated to the body element activated.

In a typical application, the BID 10 is embedded below the externalsurface of the skull. In that regard, reference is made to FIG. 8showing BID 10 located below the interior surface 76 of skull 78.Command and control signals, as previously described, are conveyedbetween brain sites monitored by electrode arrays 16 and 18 on conduit14. The materials comprising the BID 10, conduit 14 and electrode array16 and 18 are biocompatible and sealed to minimize the risk of infectionto the patient. Surgical techniques used in implanting the BID andassociated accessories are known in the art. In yet another embodiment,the BID may be located external of the skull with the conduit 14 beingplaced in position below the skull and in contact with the motor cortexand the sensory cortex.

FIG. 9 is an illustration of the placement of two electrode arrays 16and 18 used in conjunction with the BID 10 whereby electrode array 16 isdisposed over the brain's motor cortex 64 and electrode 18 is disposedover the brain's sensory cortex 66. It is to be understood that usingtwo electrode arrays is a design choice dependant upon the number ofbody elements to be controlled and the distance between thecorresponding motor cortex and sensory cortex sites. For certainapplications, where for example, only one body element is to becontrolled, attachment to both motor cortex and sensory cortex sites maybe satisfied using only a single electrode array.

To accommodate sensing rapidly occurring neurological signals samplingof such neurological signals may be undertaken at rates in the range ofabout 30,000-50,000 samples per second. This range may be expandeddepending upon the nature of the neurological signal sensed. Forexample, signals occurring during periods of very slow activity, such assleeping, may call for a much slower sampling rate, whereas periods ofvery fast activity may call for faster sampling rates. Considering asampling rate of 40,000 samples per second or 400 samples per 10milliseconds and using an 8-bit word per sample, then without any datareduction scheme the electronics contained within chip stack 44 would berequired to process 3,200 bits of information per millisecond. Althoughdoable, the electronics size requirements imposed by this data handlingcapability conflict with the miniaturization objective for chip stack 44and ultimately for the assembly 12. Accordingly, a “window circuit”consistent with the teachings put forth in U.S. Pat. No. 6,990,372 andincorporated herein in its entirety and is utilized in the electronicsof chip stack 44. The window circuit configured to include low and highmagnitude signal threshold levels coupled with a rectifying andaveraging process reduces a large number of neuron firing (neurologicalsignals) for 10 milliseconds to a much lower but representative number.The window circuit essentially may be described as event detectioncircuitry where the events are the detected magnitudes of the severalneurological signals that exceed the preselected threshold settings andfurther includes an event counter that counts the number of detectedevents over a preselected time interval. These detected events may befurther analyzed by determining the average number events per timeinterval as a measure of the detected neurological signals. For example,the 3,200 bits of information per 1 millisecond sample intervalpreviously discussed may be reduced to about 8 bits. Low and highthresholds described in U.S. Pat. No. 6,990,372 may be adjusted toachieve the above described reduction of bit information processed.Further separation of the high and low threshold values can reduce thenumber of bits in the range of 2 to 3 bits. An additional advantage ofthe data reduction resulting from the use of the window circuit is thatautocorrelation signal processing is not necessary and therefore notincorporated in the electronic processing scheme which further reducesthe amount of processing and therefore decreasing the overall size ofthe electronics necessary for chip stack 44. In effect, the windowcircuit implementation reduces the vast amount of data to an “essencesignal” by taking advantage of nerve spike signals and developing anaverage of such spike signals.

With reference now to FIG. 10 there is shown an alternate embodiment ofthe present invention. The brain implant device 100 is somewhat“mushroom” shaped having a cap portion 102 and a stem portion 104.Although not restricted to any specific material, a suitable materialfor the cap and stem portion of device 100, is zirconia. Although notrestricted to unique dimensions and shapes the cap portion 102preferably is circular in shape having a diameter 106 of about 30 mm.The stem portion 104 preferably is circular having a diameter 108 ofabout 20 mm. The stem portion 104 has an overall height dimension 110(including disk 152 and insulator 154) being about 5 mm and the device100 has an overall height dimension 112 being about 7.5 mm. The capportion 102 includes a disk shaped recess 114 extending into the cap adimension 116 being about 1.25 mm.

Disposed along the periphery of recess 114 is coil 118 as will bedescribed below. Coil 118 is adapted for magnetic coupling with anexternal time varying magnetic field for recharging energy storage meanscontained in a device 100. Located Within the recess 114 is permanentmagnet 120. Magnet 120 is positioned within the recess 114 so as tooptimize alignment of the magnetic field with respect to the coil 118 tomaximize magnetic coupling between the magnetic field and the coil. Themagnet 120 may be secured in place by any one of a number of techniquesknow in the art including, for example, an adhesive capable of adheringmetal to a ceramic material.

To seal the recess 114 from an outside environment, a cover piece 122 ispositioned to rest against circular lip 124 that extends slightly inwardin the recess to form a shelf to support cover piece 122.

The thickness of the cover piece 122 and the depth of the circular lip124 that extends (measured downward) from the outer contour surface 126of cap portion 102 is sized such that with the corner piece in place arelatively continuous outer surface 126 is maintained. The cover piece122 may be secured in place by use of a number of techniques such as,for example, a bonding material capable of bonding ceramics together atlow temperature. A candidate material for active solder joining ofceramics is S-Bond TM 200 available from Material Resource Internationalof Lansdale, Pa., USA.

Located on the inside face of cover piece 122 is an antenna 128 (nowshown in FIG. 10, see FIGS. 15-18) in accordance with the principalsdescribed for antenna 52. Although antenna 52 is described as extendingcircumferentially about coil 46 it is to be understood that antenna 128may be disposed in a number of geometries (FIGS. 15-18, as mereexamples) to accomplish the transmission reception capability of theantenna 128.

The stem portion 104 defines an interior cavity 130 sized to housedevice electronics. More particularly, cavity 130 includes battery 132comprising a structure and design similar to that of battery 40. Mountedabove battery 132 are transmitter/receiver chip 134, crystal 136 andbattery management chip 138. The battery management chip 138 providessupervisory control over the battery charge state and preventsovercharging of the battery during the charging process. Moreover, chip138 provides voltage regulation to the battery output to maintain deviceelectronics with a substantially constant voltage source. Voltagecharging control and voltage regulation is accomplished by chip 138 in amanner consistent with that described for the embodiment of FIG. 1.

Crystal 136 provides a constant frequency signal source of use in dataprocessing, timing, clocking, gating, and telemetry transmission andreceiving functions. The transmitter/receiver chip 134, crystal 136, andbattery management chip 138 are mounted on board 142. Immediatelyadjacent to board 142 is board 144 upon which is mounted capacitors 140and preamplifier and amplifier chips 146. The function oftransmitter/receiver chip 134, capacitors 140, and preamplifier andamplifier chips 146 is consistent with that described for the embodimentof FIG. 1 and thus will not be repeated here and again.

A circumferential ring 148 is position at the base 150 of stem portion104. Preferably the ring 148 is formed of a titanium material such asTi64 capable of being brazed to a ceramic material. Ring 148 is brazedto stem portion 104 using brazing techniques well known in the art. Acircular disk 152 preferably formed of Ti64 is sized to fit against ring148 and provide a complete seal between the internal region of stemportion 104 and the external environment.

The disk 152 is secured to ring 148 by means of a laser weld in a mannerto insulate the internal region of the stem portion 104 from entry ofany external fluids and the like. Attached to disk 152 is a commonmaterial insulator 154 preferably made of Kapton that extends over theentire outward facing surface of disk 152. Attachment of insulator 154to disk 152 may be accomplished by any one of a number of techniquesknown in the art.

As shown in the partial schematic view of FIG. 11, distributed acrossthe disk 152 and insulator 154 are a plurality of passage ways 156 (ofwhich only two are identified in FIGS. 10 and 11) through whichindividual conductors 158 pass from the interior of device 100 toconduit 160. An insulating material such as glass 162 is containedwithin the passage way and surrounds the conductors 158 to maintain theindividual conductors in place and electrically insulated from thecircular disk 152. The individual conductors 158 pass through theinsulator 154 and terminate at connector 164. Connector 164 may be oneof a number of separable devices permitting conduit 160 to be detachedand reattached to the connector 164. Conduit 160 is similar in structureand characteristics as conduit 14 and thus a description of conduit 160need not be repeated herein again. The conductors 158, although notshown as being coupled to preamplifier and amplifier chips 146, it is tobe understood that the conductors are routed to respective amplifiers toprovide the sensing and stimulation function provided by device 100.

Referring to FIG. 12 there is shown assembled in perspective view theunderside of device 100. As shown with the insulator 154 partially cutaway, passage ways 156 are disposed throughout circular disk 152, theconductors 158 are positioned within the insulator 154 so as to beelectrically isolated one from the other as they traverse the insulator154 and conduit 160. Although not shown, it is to be understood theconductors 158 are positioned within the device 100 from the insulator154 to respective preamplifiers and amplifiers 146.

With reference to FIG. 13 the device 100 is shown positioned in place inskull 166. For purpose of clarity, only the skull bone 166 of amammalian head is shown. In one approach a hole 168 slightly greater indiameter than the diameter of stem 104 is drilled in the skull.Subsequentially conduit 160 is placed in the interior of the skull suchthat electrode arrays 16 (and 18 if included) is positioned in contactwith the motor cortex 64 and/or sensory cortex 66 as desired. The device100 may be secured in place by a compression fit whereby the hole 168 inthe skull is marginally smaller in diameter than the diameter of thestem portion 104 and the gripping action of the skull against the stemportion 104 maintains the device 100 in place. Another one of a numberof approaches known in the art to secure device 100 to the skull is bythe use of a medical adhesive applied to the stem portion 104 withsufficient adhesive strength to keep the device 100 maintained in placewhile being sufficiently forgiving such that the device 100 may beremoved with minimal force.

As an alternative insertion method, a square notch 170 (see FIG. 14)preferably in the order of 5 mm×5 mm may be “nibbled” into the skullimmediately adjacent to the circular hole adapted to receive stem 104.The notch provides a passage way into which the electrode arrays may beinserted for placement in brain tissue. The circular hole and notch arelocated preferably in the close vicinity of selected brain tissue to becontacted for ease of location and placement of electrode arrays. Theconduit 160 may be wedged partially within the notch to stabilize theconduit from moving once attached to selected brain tissue.

Although the present invention has been described with reference tomultiple embodiments it is to be understood that still furtherembodiments are within the contemplation of the invention. As a mereexample, antenna 128 may be any one of a number shapes including, butnot limited to, the helix shown in FIG. 15, the “starburst” shown inFIG. 16, or the “zigzag” shown in FIG. 17.

What is claimed is:
 1. A brain implant system comprising an implantabledevice, the implantable device comprising: a sealed housing; electronicscontained within the housing and configured to receive and processsignals from selected sites of a brain; an energy source containedwithin the housing and configured to provide energy to the electronics;and a flexible conduit in electrical communication with the electronics,said flexible conduit having a proximal end bonded together with saidhousing to form an integrally mounted unitary structure therewith, saidflexible conduit extending from the housing and configured to contactbrain tissue for communicating signals from selected sites of the brainto said electronics, wherein the electronics includes data processingcircuitry configured to detect an attribute of the signals from selectedsites of the brain according to at least one pre-selected criteria andto designate each occurrence of the detected attribute as a detectedevent, said data processing circuitry further configured to form aprocessed value corresponding to such detected events over apre-selected interval of time.
 2. The system of claim 1 furthercomprising an external communication device, wherein the electronics areadapted for wireless communication with the external communicationdevice, said electronics further adapted to provide a measure of thesignals from selected sites of the brain to the external communicationdevice via a wireless communication link.
 3. The system of claim 2further comprising at least one implantable microdevice, wherein saidexternal communication device comprises a master controller adapted toprovide wireless communication between the implantable device and the atleast one implantable microdevice.
 4. The system of claim 3 wherein theat least one microdevice is configured to stimulate contraction of amuscle, and wherein the master controller commands the at least onemicrodevice to stimulate contraction of the muscle when the implantabledevice indicates that the signals from selected sites of the brainindicate an intention to contract the muscle.
 5. The system of claim 4wherein the at least one microdevice is configured to sense adepolarization signal emitted by the muscle, and wherein the mastercontroller commands the implantable device to provide a signal to thebrain when the microdevice senses the depolarization signal.
 6. Thesystem of claim 3 wherein the at least, one implantable microdevice isselected from the group consisting of: at least one microstimulator, atleast one microsensor, and at least one combinationmicrostimulator/microsensor.
 7. The system of claim 1, wherein saidsignals from selected sites of the brain are sampled at a predefinedrate and have a first data content measured in number of bits over thepre-selected interval of time and wherein said processed value has asecond data content measured in number of bits over the pre-selectedinterval of time, said second data content having fewer bits than saidfirst data content.
 8. The system of claim 7, wherein said dataprocessing circuitry is adapted to determine the average value of thenumber of detected events that exceed a first threshold value over thepre-selected time interval.
 9. The system of claim 8, wherein said dataprocessing circuitry is adapted to determine the average value of thenumber of detected events that exceed a second threshold value over thepre-selected time interval.
 10. The system of claim 9, wherein the firstthreshold and second threshold define a window of eligible detectedevents for processing, said data processing circuitry adapted todetermine an average number of detected events occurring within saidwindow over a pre-determined time interval.
 11. The system of claim 1,wherein the housing includes a plurality of feedthroughs and wherein theelectronics comprises a plurality of individual channels, each channeladapted for processing signals related to selected brain sites, eachchannel electrically coupled to respective ones of the feedthroughs. 12.The system of claim 11, wherein the flexible conduit distal endcomprises a plurality of electrically conductive protuberances, eachprotuberance having a tip portion, the tip portion being adapted forcontact with a desired site on the brain, and wherein the flexibleconduit proximal end comprises a plurality of electrical contactsadapted for electrical coupling to respective ones of the feedthroughs,and a conductor portion extending between the distal end and theproximal end, the conductor portion including a plurality ofelectrically conductive wires, each wire coupled between respective onesof the protuberances and the proximal end electrical contacts andadapted to convey signals between the protuberances and the proximalend.
 13. The system of claim 12, wherein the conductive wires areselected from the group consisting of platinum, gold and copper andalloys thereof.
 14. The system of claim 13, wherein the flexible conduitis configurable in a serpentine zig-zag fashion to provide contractionand extension thereof without dislodging the protuberances from brainsites.
 15. The system of claim 11, wherein the energy source comprises arechargeable battery and wherein each channel is electrically coupled tosaid battery to receive energy therefrom.
 16. The system of claim 15,wherein the implantable device further comprises: a coil disposed withinthe housing; and charging circuitry coupled to the coil and therechargeable battery, said charging circuitry configured to controldelivery of energy to said rechargeable battery, said coil responsive toan external alternating magnetic field and adapted for supplying energyto said rechargeable battery via said charging circuitry.
 17. The systemof claim 16, wherein the implantable device further comprises a magnetpositioned within the device and in proximity to the coil so as toconcentrate the external alternating magnetic field for optimizingcoupling between said magnetic field and the coil.
 18. The system ofclaim 1 further comprising an implantable communication device, whereinthe electronics are adapted for wireless communication with theimplantable communication device, said electronics further adapted toprovide a measure of the signals from selected sites of the brain to theimplantable communication device via a wireless communication link. 19.The system of claim 18 further comprising at least one implantablemicrodevice, wherein the implantable communication device comprises amaster controller adapted to provide wireless communication between theimplantable device and at least one implantable microdevice.
 20. Thesystem of claim 19 wherein the at least one microdevice is configured tostimulate contraction of a muscle, and wherein the master controllercommands the at least one microdevice to stimulate contraction of themuscle when the implantable device indicates that the signals fromselected sites of the brain indicate an intention to contract themuscle.
 21. The system of claim 20 wherein the at least one microdeviceis configured to sense a depolarization signal emitted by the muscle,and wherein the master controller commands the implantable device toprovide a signal to the brain when the microdevice senses thedepolarization signal.
 22. The system of claim 19 wherein the at leastone implantable microdevice is selected from the group consisting of: atleast one microstimulator, at least one microsensor, and at least onecombination microstimulator/microsensor.
 23. The system of claim 1further comprising at least one implantable microdevice, wherein theelectronics are adapted for wireless communication with the at least oneimplantable microdevice, said electronics further adapted to provide ameasure of the signals from selected sites of the brain to the at leastone microdevice via a wireless communication link.
 24. The system ofclaim 23, wherein the at least one implantable microdevice comprises aplurality of implantable microdevices, and wherein the implantabledevice communicates with each one of the plurality of implantablemicrodevices via the wireless communication link.
 25. The system ofclaim 23 wherein the at least one microdevice is configured to stimulatecontraction of a muscle when the implantable device indicates that thesignals from selected sites of the brain indicate an intention tocontract the muscle.
 26. The system of claim 25 wherein the at least onemicrodevice is configured to sense a depolarization signal emitted bythe muscle, and wherein the implantable device provides a signal to thebrain when the microdevice senses the depolarization signal.
 27. Thesystem of claim 23 wherein the at least one implantable microdevice isselected from the group consisting of: at least one microstimulator, atleast one microsensor, and at least one combinationmicrostimulator/microsensor.
 28. The system of claim 1 wherein theselected sites of the brain comprise a motor cortex and a sensorycortex.
 29. The system of claim 1 wherein the sealed housing isimplantable below the interior surface of a skull housing the brain.